Tissue expanders and methods of use

ABSTRACT

Tissue expanders and their methods of use.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. application Ser. No.12/973,693, filed Dec. 20, 2010; which claims the benefit of U.S.Provisional Application No. 61/288,197, filed Dec. 18, 2009; and

Said U.S. application Ser. No. 12/973,693, filed Dec. 20, 2010, is alsoa continuation-in-part application of U.S. application Ser. No.11/231,482, filed Sep. 21, 2005, which claims the benefit of U.S.Provisional Application No. 60/612,018, filed Sep. 21, 2004, and U.S.Provisional Application No. 60/688,964, filed Jun. 9, 2005.

All of the aforementioned applications are incorporated by referenceherein.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare incorporated by reference herein to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

BACKGROUND

A deficit of normal tissue in a subject may result from, for example,burns, tumor resection surgery (e.g. mastectomy), or congenitaldeformities. Often, the tissue in deficit is skin and/or underlyingconnective tissue. The tissue in deficit can also be an intrabody duct(e.g. urethras or GI tract).

One method of correcting skin deficit is to stimulate creation of newskin. Implantation of a device that expands and stretches the existingskin causes a growth response in which new skin is created. While theexact physiologic mechanism of this response is not fully understood,clinical success has been reported for many years.

The formal concept of surgical tissue expansion was first reported byNeumann in 1957, in which a rubber balloon, attached to a percutaneoustube, was implanted to enable intermittent expansion for the purpose ofreconstructing a partially amputated ear. The concept of tissueexpansion was further refined and popularized for breast reconstructionby Radovan and Argenta in the 1980's. Despite many advantages of thetechnique, most notably minimal additional surgical dissection andpatient downtime, the out-patient process remains lengthy and onerous,often involving months of weekly office visits and discomfort resultingfrom the relatively high pressures associated with periodic expansion byfilling with saline. Most commercially available tissue expandersfunction as an implantable balloon with a separate or imbedded valvethat allows periodic filling. Typically, a physician performs thefilling procedure. The filling events are relatively infrequent (e.g.,weekly), and therefore a significant expansion pressure is typicallyapplied at each doctor's visit to achieve a maximum effect from eachvisit. As a result of this expansion pressure during a clinic visit, arelatively sudden tissue stretch occurs. This may cause subjects tosuffer discomfort and/or tissue ischemia. The relatively large expansionpressure can also adversely affect underlying structures, such ascausing concavities in underlying bone. In addition, high pressure maycreate restrictive capsules around the implant and/or cause tissuefailure. Some previously available alternatives used a percutaneousneedle for inflation or filling or inflation, creating a potentialsource of infection.

Gradual, continuous expansion was introduced and thought to overcomemany of the drawbacks associated with periodic saline injections. Forexample, osmotic expanders have been reported by Austad in 1979, Bergein 1999, and Olbrisch in 2003 (see U.S. Pat. Nos. 5,005,591 and5,496,368). A commercial version is available from Osmed Corp. in alimited range of sizes. These devices use a polymeric osmotic driver toexpand a silicone implant by absorbing interstitial fluid (“ISF”). Apotential problem of such devices is the lack of control oradjustability after implantation with respect to expansion variablessuch as pressure, volume, onset of expansion, and end of expansion oncethey have been deployed. U.S. Pat. No. 6,668,836 to Greenberg et al.describes a method for pulsatile expansion of tissue using an externalhydraulic pump. The external hydraulic pump is bulky and inconvenientfor patients. The percutaneous attachment reduces patient mobility andmay be a source of contamination. U.S. Pat. No. 4,955,905 to Reedteaches an external monitor for pressure of an implanted fluid filledtissue expansion device. U.S. Pat. Nos. 5,092,348 and 5,525,275 toDubrul and Iverson, respectively, teach implantable devices withtextured surfaces. Some other devices use mechanical orelectromechanical forces to avoid having to use fluids for tissueexpansion.

Widgerow tested a continuous expansion device using an external pumpconnected through tubing to the implanted expander that allowed completepatient control. This provided rapid time courses and patientsatisfaction. However, the connector tubing imparts both a cumbersomesetup for the patient as well as the fear that prolonged connectionbetween the external environment and the implanted device may lead tocontamination. As the expanded space ultimately receives a permanentimplant, any level of contamination is considered unacceptable.

Despite the advent and acceptance of breast conservation treatmentmodalities for breast cancer, mastectomy remains the treatment of choicefor breast cancer in several clinical settings. These include situationsin which there is an inability to achieve clean margins withoutunacceptable deformation of the remaining breast tissue, multipleprimary tumors, previous chest wall irradiation, pregnancy, or severecollagen vascular diseases (e.g., lupus). Mastectomy is also indicatedfor women at high risk due to the presence of BRCA1 or BRCA2 orcontralateral disease. Many such women are candidates for breastreconstruction and opt for reconstructive surgery at the time ofmastectomy or in a delayed fashion after healing. According to theAmerican Society of Plastic Surgery statistics, 57,102 U.S. patientsunderwent breast reconstruction in 2007.

Prosthetic reconstruction of the breast, as a staged procedure withtissue expanders followed by implants, is a reliable method for breastreconstruction that offers favorable aesthetic and psychological resultswhile adding only minimal additional surgical intervention. Today, theprocess usually involves the placement of a tissue expander device underthe pectoralis major muscle and remaining skin of the absent breast. Thedevice is then gradually inflated over several weeks or months byperiodic injections of saline, causing the stretching and expansion ofthe overlying skin and muscle coverage. When adequate coverage isachieved, the expansion device is typically removed, and a permanentbreast implant is placed into the expanded space.

A significant clinical advantage would be realized if tissue expanders,such as breast tissue expanders, could provide any or all of thefollowing: the elimination of technical problems associated with earlierdevices while allowing greater patient comfort, control, speed, overalluser friendliness, continuous or near continuous expansion, completesurgeon-patient control, and the eradication of percutaneouscommunication with the external environment which can lead to infection.

SUMMARY

One aspect of the disclosure is a tissue expansion system, including animplantable device adapted to be implanted within a patient, wherein theimplantable device has an anterior portion, a posterior portion, aninferior portion, and a superior portion, and wherein the implantabledevice comprises a communication component secured in the superior andanterior portions, and an external device adapted to be disposedexternal to the patient to wirelessly communicate with the communicationcomponent to control the expansion of the implantable device.

In some embodiments the implantable device includes an inner layerdefining an expandable chamber, wherein the inner layers comprises apreformed shape that defines the anterior, posterior, inferior, andsuperior portions, and wherein the communication component is secured tothe superior and anterior portions of the inner layer. The inner layercan comprise an inelastic material. The inner layer can have a preformedgeneral breast configuration defining the anterior, posterior, inferior,and superior portions, and wherein the communication component issecured to the anterior and superior portions of the general breastconfiguration. The general breast configuration can have a lower poleand an upper pole, wherein the upper pole is disposed in the superiorportion, wherein the lower power has a thickness greater than athickness of the upper pole, and wherein the communication component issecured within the upper pole.

In some embodiments the system further comprises a fluid reservoirwithin an inner chamber of the implantable device, wherein thecommunication component and the fluid reservoir are in communication,and wherein the external device is adapted to wirelessly communicatewith the communication component to controllably release fluid from thefluid reservoir into the inner chamber. The communication component caninclude an antenna.

One aspect of the disclosure is a method of expanding tissue. The methodincludes an implantable device implanted with a patient, the implantabledevice comprising an expandable chamber, a fluid reservoir, and acommunication component, positioning a remote controller proximate thebodily region in which the implantable device is implanted, andactuating the remote controller to expand a lower pole of the expandablechamber to have a greater projection than an upper pole of theexpandable chamber. In some embodiments expanding the lower pole expandstissue adjacent the lower pole, and expanding the upper pole expandstissue adjacent the upper pole, and wherein expanding the lower pole tohave a greater projection than the upper pole comprises expanding thetissue adjacent the lower pole to a greater extent than the tissueadjacent the upper pole. In some embodiments the expandable chamber hasa preformed configuration in which the lower pole has a projection thatis greater than a projection of the upper pole, and wherein actuatingthe remote controller expands the expandable chamber towards thepreformed configuration. In some embodiments actuating the remotecontroller expands the expandable chamber towards a general breastconfiguration. In some embodiments the implantable device comprisesanterior, posterior, superior, and inferior portions, and whereinpositioning the remote controller proximate the bodily region in whichthe implantable device is implanted comprises positioning the remotecontroller adjacent the superior and anterior portions.

One aspect of the device is a breast implant that includes aself-contained implantable device adapted to be implanted within breasttissue of a patient, wherein the implantable device has a substantiallyinelastic portion having a general breast configuration.

In some embodiments the substantially inelastic portion comprises atleast the curved portions of the general breast configuration. Thesubstantially inelastic portion can additional comprise a generally flatposterior portion of the breast configuration. The anterior andposterior portions can be two different components secured together. Insome embodiments the substantially inelastic portion at least partiallydefines an inner chamber in which a fluid is contained. In someembodiments the fluid is saline, and in some embodiments the fluid is agas. In some embodiments the implant further comprises a gas reservoirdisposed completely within the inner chamber. In some embodiments theimplant further comprises a communication component disposed completelywithin the inner chamber adapted to wirelessly communicate with a deviceexternal to the patient. In some embodiments the external device isadapted to be actuated to control the release of gas from the gasreservoir into the inner chamber to expand the inner chamber. In someembodiments the general breast configuration includes an inferiorportion and a superior portion, and wherein the inferior portion has amaximum projection dimension that is greater than a maximum projectiondimension of the superior portion.

One aspect of the disclosure is a tissue expansion system including animplantable device comprising an expandable compartment and a gassource, wherein the gas source is secured within the expandablecompartment but is not rigidly fixed relative to the expandablecompartment to allow for relative movement between the gas source andthe expandable compartment after the implantable component is positionedwithin a patient, and an external device adapted to control the releaseof gas from the gas source into the expandable compartment from alocation external to the patient. In some embodiments the implantabledevice comprises a gas source retention element, at least a portion ofwhich is fixidly secured to the expandable compartment, and wherein thegas source is secured to the expandable component using the gas sourceretention element. The gas source retention element can be a film layer,at least a portion of which is fixidly secured to the expandablecompartment, and wherein the gas source is secured within the filmlayer. At least a portion of the gas source retention element can befixed to a posterior portion of the expandable compartment. The gassource retention element and the gas source can form a hammock design.

One aspect of the disclosure is a tissue expansion system including animplantable device comprising a fluid source and an expandable chamber,an external controller adapted to wirelessly communicate with theimplantable device to control the release of fluid from the fluid sourceinto the expandable chamber to expand the expandable chamber, and aprocessing component adapted to compare the number of times fluid hasbeen released from the fluid source within a given period of time with amaximum number of times fluid is allowed to be released from the fluidsource within the given period of time. In some embodiments theprocessing component is disposed within the external controller. Theprocessing component can be further adapted to prevent the release offluid from the fluid source if the number of times fluid has beenreleased from the fluid source within the given period of time isgreater than or equal to the maximum number of times that fluid isallowed to be released from the fluid source within the given period oftime. The processing component can be adapted to prevent the fluidsource from releasing fluid more than 3 times within about a 24 hourperiod. The processing component can be adapted to prevent the fluidsource from releasing fluid more than once about every 3 hours.

In some embodiments the external controller is adapted to communicatewith the implantable device upon actuation of the external controller tocontrol the release of fluid from the fluid source, and wherein theprocessing component is adapted to compare the number of times theexternal controller has been actuated within a given period of time witha maximum number of times the external controller can be actuated withinthe given period of time. The fluid source can be a compressed gassource.

One aspect of the disclosure is a tissue expansion system, including animplantable device comprising a gas source and an expandable chamber, anexternal controller adapted to wirelessly communicate with theimplantable device to control the release of fluid from the fluid sourceinto the expandable chamber to expand the expandable chamber, and aprocessing component adapted to compare the volume of fluid that hasbeen released from the fluid source within a given period of time with amaximum volume of fluid that is allowed to be released from the fluidsource within the given period of time.

In some embodiments the processing component is disposed within theexternal controller. The processing component can be further adapted toprevent the release of fluid from the fluid source if the volume offluid that has been released from the fluid source within the givenperiod of time is greater than or equal to the maximum volume of fluidthat is allowed to be released from the fluid source within the givenperiod of time. The processing component can be adapted to prevent thefluid source from releasing more than about 30 mL of fluid within about24 hours. In some embodiments the fluid source is a compressed gassource.

One aspect of the disclosure is a tissue expansion system including animplantable device comprising a fluid source and an expandable chamber,an external controller adapted to wirelessly communicate with theimplantable device in response to actuation of the external controllerto control the release of fluid from the fluid source into theexpandable chamber to expand the expandable chamber, and a processingcomponent adapted to prevent more than a maximum volume of fluid frombeing released from the fluid source upon a single actuation of theexternal controller. In some embodiments the processing component isdisposed within the external controller. The processing component can beadapted to prevent more than about 10 mL of fluid from being releasedupon a single actuation of the external controller. The system caninclude a memory component that logs an event if more than the maximumvolume of fluid is released from the fluid source upon a singleactuation of the external controller.

One aspect of the disclosure is a tissue expansion system, including animplantable device comprising a fluid source and an expandable chamber,an external controller adapted to wirelessly communicate with theimplantable device to control the release of fluid from the fluid sourceinto the expandable chamber to expand the expandable chamber, and aprocessing component adapted to compare the total volume of fluidreleased from the fluid source into the expandable chamber with amaximum fill volume for the implantable device. In some embodiments thefluid source is a gas source. The processing component can be disposedwithin the external controller. The processing component can be furtheradapted to prevent the release of fluid from the fluid source if thetotal volume of fluid that has been released from the fluid source isgreater than or equal to the maximum fill volume for the implantabledevice. The processing assembly can be adapted to prevent the release offluid from the fluid source if a total of about 350 mL to about 1040 mLof fluid has been released from the fluid source.

One aspect of the disclosure is a tissue expansion system including animplantable device comprising a fluid source and an expandable chamber,an external controller adapted to wirelessly communicate with theimplantable device to control the release of fluid from the fluid sourceinto the expandable chamber to expand the expandable chamber, and aprocessing component adapted to compare a total volume of fluid releasedfrom the fluid source into the expandable chamber with a maximum fillvolume for the implantable component, wherein the processing componentis adapted to automatically adjust the total volume of fluid releasedfrom the gas source into the expandable chamber to account for a volumeof fluid that has permeated out of the expandable chamber.

In some embodiments the fluid source is a compressed carbon dioxide(CO2) reservoir, and the processing component is adapted toautomatically adjust the total volume of carbon dioxide released fromthe carbon dioxide reservoir into the expandable chamber to account fora volume of carbon dioxide that has permeated out of the expandablechamber. The processing component can be adapted to automatically causethe release of fluid from the fluid source to compensate for the volumeof fluid that has permeated out of the expander chamber.

One aspect of the disclosure is a tissue expansion system including animplantable device comprising a gas source, an expandable chamber, and apressure relief valve adapted to release gas from the expandablechamber, and an external controller adapted to communicate with theimplantable device to control the release of gas from the gas sourceinto the expandable chamber to expand the expandable chamber. In someembodiments the external controller comprises an actuator that isadapted to open the relief valve upon actuation thereof to release gasfrom the expandable chamber. The external controller can comprise asecond actuator that is adapted to be actuated by control the release ofgas from the gas source. The implantable device can comprise a pressuresensor adapted to sense when the pressure within the expandable chamberexceeds a maximum allowable pressure, and wherein the pressure reliefvalve is adapted to automatically open to release a volume of gas fromthe expandable chamber. The external controller can comprise a pressuresensor adapted to sense when the pressure within the expandablecomponent exceeds a maximum allowable pressure. The pressure reliefvalve can comprise a first magnetic component, and wherein the systemfurther comprises relief valve actuator comprising a second magneticcomponent, wherein the second magnetic component is adapted to interactwith the first magnetic component to open the relief valve and releasegas from the expandable chamber.

One aspect of the disclosure is a tissue expansion system including animplantable device comprising a fluid source, an expandable chamber, andan intrinsic port, wherein the fluid source is in fluid communicationwith the expandable chamber, and an external controller adapted towirelessly communicate with the implantable device to control therelease of fluid from the fluid source into the expandable chamber toexpand the expandable chamber, wherein the intrinsic port is adapted toallow a removal device to be inserted therethrough to remove fluid fromthe expandable chamber. In some embodiments the removal device is aneedle, and the intrinsic port is adapted to re-seal after the needle isinserted therethrough to remove fluid from the expandable chamber. Theintrinsic port can be adapted to allow the implantable device to bere-filled with a second fluid, such as saline, after the fluid isreleased from the expandable chamber. The external controller can beadapted to wirelessly communicate with the implantable device to controlthe release of fluid from the fluid source after the removal of thefluid from the expandable chamber. The implantable device can furthercomprise a communication component, and wherein the instrinsic fill portis disposed adjacent the communication component. The implantable devicecan comprise an outer shell and an inner bag, wherein the intrinsic portis formed in the outer shell. The implantable device can comprise anouter shell and an inner bag, wherein the intrinsic port is disposedwithin the inner bag.

One aspect of the disclosure is a method of removing fluid from animplant, including removing a gas from a self-contained implantpositioned within breast tissue, wherein removing the fluid comprisesadvancing a needle through an intrinsic port within the self-containedimplant and removing fluid through the needle, and after a radiationtherapy has been performed on the patient, re-filling the self-containedimplant with a second fluid. The second fluid can be saline. Re-fillingthe self-contained implant with a second fluid can comprise positioninga needle through the intrinsic port and advancing the second fluidthrough the needle and into the implant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary tissue expansion system including animplantable device and a remote controller.

FIGS. 2 and 3 illustrate a portion of an exemplary implantable device inwhich the fluid source is not rigidly fixed to the expandablecompartment.

FIG. 4 illustrates an exploded view of a portion of an exemplaryimplantable device.

FIG. 5 illustrates an exemplary outer shell in which portion of theshell have a greater thickness than other portions of the shell.

FIG. 5A illustrates an exemplary implantable device with a generalbreast-shaped expandable compartment.

FIG. 6 illustrates an exemplary driver.

FIGS. 7A-7E show features of an exemplary valve orifice.

FIG. 8 illustrates remanence force vs. solenoid core offset.

FIG. 9 illustrates an exemplary solenoid current measured over time,indicating the valve opening time.

FIGS. 10A-C illustrate an exemplary magnetic enhancement padincorporated into a valve spring.

FIG. 11 illustrates an alternative embodiment of a magnetic enhancementpad.

FIG. 12 shows an exemplary remote controller with a master keypositioned therein.

FIGS. 13 and 14 show an exemplary physician quick reference and apatient quick reference for using exemplary expansion systems.

FIGS. 15A-15H illustrate exemplary relief valve concepts.

FIGS. 16 and 17 show an exemplary embodiment of a pressure relief valvethat can be incorporated into a tissue expansion system.

FIGS. 18A-C illustrate an exemplary mechanism for releasing a fluid fromone or more regions of a tissue expander and for filling a region of thetissue expander with a fluid.

FIG. 19 illustrates an exemplary mechanism to remove fluid from a regionof a tissue expander.

FIG. 20 illustrates an exemplary mechanism to remove fluid from a regionof a tissue expander.

FIGS. 21A-24B illustrate exemplary embodiments of an implant with anintrinsic needle port.

FIGS. 25A-D illustrate an exemplary method of sterilizing a tissueexpander.

DETAILED DESCRIPTION

The disclosure herein relates to tissue expanders and methods of usingtissue expanders. In some embodiments the tissue expanders are used toexpand breast tissue, but the tissue expanders can be used to expandtissue in other areas of the body. In some embodiments a tissueexpansion system includes an implantable assembly, or implant, and aremote controller, which is adapted to remain external to the patientand can be actuated by the patient to wirelessly control the expansionof the implantable portion. Expansion of the implantable portion causesthe expansion of tissue in the region of the body in which theimplantable portion is positioned.

FIG. 1 illustrates an exemplary embodiment of a tissue expansion system.Tissue expansion system 10 includes implantable portion 20 (alsoreferred to herein as “implant”) and remote controller 30. In thisembodiment the implantable portion has a general breast shape orconfiguration and is adapted for breast reconstruction following, forexample, mastectomy. Implantable portion 20 includes outer shell 22 andan inner bag, which comprises anterior portion 23 and posterior portion21. A portion of the outer shell and the anterior portion of the innerbag are shown removed to illustrate additional components of theimplant. The inner bag defines an expandable inner chamber, orcompartment. Implant 20 also includes fluid reservoir and valve 24 (whencombined are commonly referred to herein as a “driver”), as well ascommunication component 25. The driver and the communication componentare positioned completely within the inner bag and secured thereto,either directly or indirectly. In FIG. 1, driver 24 is secured to cradle26, which is secured to posterior portion 21 of the inner bag.

Tissue expansion system 10 also includes remote controller 30, which isgenerally adapted to wirelessly communicate with and provide power tothe implantable portion via communication device 25 to control therelease of fluid from the fluid reservoir into the expandable innerchamber. Remote controller includes housing 31, actuator 32, and output33. Actuator 32 is shown as an actuatable button, while output 33 isshown as a plurality of visual indicators (e.g., LEDs). The actuator inthe remote controller can be any other suitable actuator (e.g., a knob,a microphone adapted to receive a user's voice as input, etc.). Theoutput can provide any number of different types of output tocommunicate information, such as, for example, visual, audio, tactile,etc.

FIGS. 2-3 illustrate exploded views of a portion of an alternativeembodiment of an implantable portion. FIG. 3 illustrates in greaterdetail the alignment of the components of the assembly. FIG. 2illustrates generally the posterior portion of the inner bag and themanner in which the driver is secured thereto. The portion of implant 40illustrates a general “hammock” design which allows the driver to besecured to the implant but where it is not rigidly fixed to theexpandable chamber. This design provides for a greater degree ofmovement between the driver and the inner bag. The embodiment in FIG. 2also reduces the “height,” or projection of the driver in the anteriordirection. The portion of the implant shown includes film band 41,hammock 43, driver 46, posterior panel barrier film 47, posterior panel52, sheeting material 48, barrier ring 49, and outer patch 50. In amerely exemplary embodiment, the components are made of the followingmaterials: film band 41 is a polyethylene film; hammock 43, whichincludes film 44, is a polyethylene film, posterior panel barrier film47 is a polyethylene/polyvinylidene chloride (“PVDC”) film; sheetingmaterial 48 is a textured silicone material; barrier ring 49 is apolyethylene/PVDC film; and outer patch 50 is a silicone material.

In an exemplary assembly of the implant shown, ends 42 of film band 41are heat-staked to posterior panel barrier film 47 at seal areas 53(shown in FIG. 3). Seal area 45 of film 44 is heat-staked to posteriorpanel barrier film 47 at seal area 54. The heat-staking secures hammock43 to posterior panel barrier film 47. End 45 of hammock 43 issuperiorly positioned to allow driver 46 to “hang” within hammock 43.Barrier ring 49 is heat-staked to posterior panel 52 at the eight (8)seal areas 51 (only one is shown in FIG. 3), which secures siliconsheeting material 48 between barrier ring 49 and posterior panel 52.Outer patch 50 is secured to sheeting material 48 using siliconeadhesive. Once assembled the portion of the implant 40 can then besecured to the rest of the implant (e.g., the anterior portion of theinner bag and the outer shell).

In the embodiment shown in FIGS. 2 and 3, the height, or projection, ofthe driver is reduced. Because the driver is not rigidly fixed to theinner expandable compartment, it has more flexibility within theimplant. The position of the driver can be slightly adjusted relative toparts of the anatomy to relieve discomfort caused by the driver. Forexample, the driver can pivot, or rock, if it is located on top of abony rib, thereby reducing discomfort to the patient. This arrangementallows the driver to be secured to the expandable chamber without beingrigidly fixed thereto. While this design does provide for movement ofthe driver within the implant, film band 41 acts to prevent the driverfrom moving around too much due to patient movement (e.g., jumping,driving over bumpy terrain, etc.).

FIG. 4 illustrates an alternative embodiment of an implantable portion(driver and implant antenna not shown). The inner bag includes generallybreast-shaped anterior portion 65, which has a perimeter seal 66 with aserpentine cut that creates a plurality of fingers 67. The inner bagalso includes posterior portion 72, which also has a serpentine cutaround a perimeter seal to create a plurality of fingers 71. In anexemplary method of manufacturing, phone dial film 74 is heat staked toposterior portion 72 through phone dial 73. Hammock 69 and band 68 areheat staked to the inner surface of posterior portion 72 as in theembodiment in FIGS. 2 and 3. The perimeter of anterior portion 65 isheat staked to the perimeter of posterior portion 72, forming the innerexpandable chamber. The inner bag, once assembled, is then placed withinouter shell 61, which comprises anterior portion 62 and posteriorportion 63. Anterior portion 62 and posterior portion 63 can beintegral, or they can be separate components secured together.Identifier 75, which can include information identifying the implant, issecured to phone dial 73 after the inner bag is placed within shell 61.The implant also optionally includes at least one suture tab 64, whichcan be used to help secure the implant to tissue within the subject.Sutures can be used to secure the suture tabs to tissue within thepatient, thereby securing the implant within the patient. The suturetabs 64 can be secured to the implant after assembly with adhesive, suchas silicon adhesive.

In some embodiments the perimeter formed when the perimeters of anteriorportion 65 and posterior portion 72 are heat staked together can becomerigid and may cause discomfort when implanted. The embodiment in FIG. 4includes serpentine cuts in the perimeters of both anterior portion 65and posterior portion 72, which create the fingers described above, toreduce the amount of rigidity in this region. In some embodiments all ofthe fingers are heat staked together, while in some embodiments lessthan all of the fingers are heat staked. In some embodiments at leastone of the fingers is cut off or trimmed to reduce the stiffness of thefinger region.

In one or more exemplary embodiments, the components of the implantableportion can be made from the following materials: the outer shellcomprises silicone rubber; the suture tabs comprise silicone rubber withpolyester (Dacron) reinforcement; the inner bag is a barrier film; thehammock and the band are either polyethylene or barrier film; and thephone dial and the phone dial film are silicone rubber.

FIG. 5 illustrates an alternative outer shell wherein a portion of theshell is thicker than other portions of the shell. Shell 76, into whichan inner bag is to be placed (see FIG. 4), is thicker in regions 77 thanin regions 78. The thicker regions 77 include the posterior backing ofthe shell and regions adjacent to the posterior backing. The thickenedregions provide protection for the patient from the fingers (see FIG.4), which can be slightly rigid and cause discomfort when the implant isimplanted. The shell can be adapted to be thicker is additional regionsas well if there are any other components associated with the inner bagthat may provide discomfort to the patient.

In the embodiments in which the fluid is CO₂, the inner bag provides abarrier to CO₂ after it has been released from the gas reservoir.

In some embodiments the inner bag or chamber is non-elastic and ispre-formed in an anatomical shape, such as, for example withoutlimitation, a breast. The inner chamber will expand to the anatomicalshape when the fluid is released from the reservoir into the internalchamber. This responds unlike a liquid-filled elastomeric balloon, whichdoes not have a preformed shape to which the balloon expands when filledwith a liquid. When the inner bag has a preformed shape of a breast, theexpanded shape emphasizes lower pole expansion where tissue generationis particularly desired during breast reconstruction so that the skinassumes the shape of a breast. FIGS. 1 and 4 are exemplary embodimentsin which a substantially inelastic portion of the implant has a breastconfiguration or shape. In particular, in these embodiments the innerchamber is the inelastic component that has the general breast shape.

In some embodiments the inner bag comprises multiple layers of materialthat are sandwiched together to form the inner bag. Exemplary materialswhich may be utilized in the inner bag can be found in U.S. Pat. App.Pub. 2006/0069403, filed Sep. 21, 2005, which is incorporated herein byreference. In some embodiments the inner bag roughly has the thicknessof a piece of paper, and while it has the ability to stretch arelatively small amount, it does not have properties like an elasticfilm. To form the inner bag in the desired anatomical shape, any layerswhich make up the inner bag are positioned adjacent one another with thedesired layering, heated, applied to a mold which has the desired shape,and then allowed to cool on the mold. The mold is then removed. In theembodiment in FIG. 4, for example, any layers that make up anteriorportion 85 can be formed on a mold as described above.

Using a non-elastic inner layer also prevents the implant from expandinginto undesirable shapes since the inner bag will tend to expand into itspre-formed shape. This is unlike, for example, a hot-dog shapedelastomeric balloon, which, if squeezed in the middle, will become adog-bone shaped balloon. Forming the inner bag in the shape of a breast,for example, prevents the implant from expanding laterally (under anarm) or superiorly (toward the clavicle). The shape of the tissue to beexpanded can therefore be controlled by forming the inner bag into aparticular shape.

In some embodiments the fluid source is a gas source, and in someembodiments the gas is, for example without limitation, CO₂. In someembodiments the gas reservoir has an internal volume of about 1 cc toabout 50 cc, and in some embodiments is about 2 cc to about 10 cc. In anexemplary embodiment, a compressed gas source has a total internalvolume of about 5 ml. Optionally a large tissue expansion may beachieved by providing about 2.5 grams of CO₂ in a 5 ml internal-volumecontainer. This provides about 1200 ml of CO₂ at 15.5 PSI (0.8 PSI aboveatmosphere at sea level). The exact amounts may vary, but in someembodiments a constant ratio can be used. For example, for every 1 mL ofinternal volume container filled with 0.5 grams of CO₂ gas, there isabout 240 mL final volume (at 0.8 PSI). The reservoir can be encased ina leak-free canister.

The outer shell generally provides a tissue interface for theimplantable device. In some embodiments the outer shell is comprised ofsilicone, but can be made of any other suitable material. It can besmooth, but in some embodiments the outer shell is textured to helpstabilize the implant within the patient. When the outer shell is asilicone outer shell, the silicone outer shell provides littleresistance to the permeation of CO₂.

The implantable portion of the tissue expansion system includes acommunication component, which can include an antenna, to facilitatecommunication with the remote controller. In some embodiments thecommunications component is secured to an anterior portion of the innerbag to provide for the easiest coupling between the remote controllerand the antenna when the remote controller is held close to thepatient's body in the region in which the implant is positioned. Forexample, in the embodiment in FIG. 1, communications component 25 issecured to the anterior portion of the inner bag. Communicationscomponent 25 is also secured to a superior portion of the inner bag,which can make it easier for the remote controller to communicate withthe communications portion of the implant.

FIG. 5A illustrates an exemplary implant 500, which includes inner bag502 (outer shell not shown) with a section removed to revealcommunications component 504 and driver 506, both of which are securedto inner bag 502. Implant 500 also includes suture tabs 508 (a third tabis not shown). In general, the inner bag has anterior and posteriorportions as indicated. In this embodiment, the posterior portiongenerally refers only to the backing, or the generally flat portion, ofthe inner bag. The curved portions of the inner bag are generallyconsidered the anterior portion. Additionally, the inner bag has aninferior portion and a superior portion as shown. The implant can beconsidered to be divided into 4 quadrants, based on the planesseparating the anterior/posterior portions and the superior/inferiorportions. As shown, the antenna is secured to the anterior portion andthe superior portion of the inner bag to make the coupling between theremote controller (not shown) and communication component 504 asefficient as possible.

In embodiments in which the inner bag has a preformed expandedconfiguration, the communication component is attached to a complex3-dimensional shape in which the inner bag is formed. The communicationcomponent, however, has the ability to deform the shape of the inner bagwhen secured thereto due to the weight and stiffness of thecommunication component. In some embodiments, in order to secure thecommunication component to the inner bag without altering the shape ofthe inner bag, the communication component is first encapsulated in afilm layer, which is then secured to the inner bag. During attachment ofthe encapsulated communication component, the formed membrane has theability to provide an approximately uniform amount of pressure over thecommunication component while it is attached to the inner bag. Amaterial such as an ESCAL™ bag can be used as the membrane to providethe necessary amount of pressure to the encapsulated communicationcomponent while being laminated to the inner bag. This will prevent theinner bag from losing its preformed shape. Additionally, thecommunication component is positioned on the anterior portion of theinner bag to maintain its position as close as possible to the surfaceof the patient. This improves the communication component'selectromagnetic coupling with the remote controller.

The implant also includes a driver, which comprises a fluid reservoirand a valve, which controls the flow of fluid from the reservoir. Insome embodiments the fluid reservoir is a compressed gas source.Actuation of the remote controller can open the valve to controllablyreleases gas from the reservoir into the inner chamber. In someembodiments the valve is a solenoid valve. FIG. 6 illustrates a sidecross-sectional view of an exemplary driver. Driver 80 includes CO₂canister 89 screwed into capillary plate 87, with seal 88, shown as awasher, forming a gas tight seal between the CO₂ canister and thecapillary plate. In some embodiments the canister and capillary plateare metal and the seal is a metal washer. Because the device is smallcompared to larger pressure vessels, the amount of force necessary to“crush” the seal (i.e., the metal washer) and make contact between themetal surfaces can easily be generated. When the canister is screwedinto the capillary plate, contact 90 of the canister and contact 91 ofthe capillary plate blank come into contact with the metal washer suchthat there is metal-on-metal contact, and the metal washer creates agas-tight seal around the two contact points. The threads on thecanister and capillary plate also enhance the seal. Additionally, a sealcreated by metal-on-metal contact between the two contact points and thethreads doesn't rely on an elastomeric member such as an O-ring (throughwhich CO₂ can permeate) to seal off the passage between two metalmembers, and thus the metal-on-metal contact between points 90 and 91with seal 88 around the contact creates a much better gas-tight sealthan simply using an O-ring to create the seal. Additional exemplarydriver components that can be incorporated into any of the systemsherein can be found described in U.S. application Ser. No. 11/231,482,which is incorporated by reference herein.

Driver 80 also includes solenoid housing 82, core 84, coil 85, andspring/seal assembly 86. The center of spring/seal assembly 86 isactuated to the left in the figure in response to a magnetic fieldgenerated by current being passed through coil 85. The leftward movementof the center of the spring/seal assembly opens the outlet to the valveorifice, allowing the release of the CO₂. Stopping the electricalcurrent through the coil causes the magnetic field to cease, thuscausing the spring assembly and rubber seal to return to a positionwhich closes off the orifice. This stops the release of CO₂.

In the exemplary embodiment shown in FIG. 6, capillary plate 87 and thevalve orifice are made from one piece, or are integral with one another.In some embodiments the capillary plate is stainless steel. FIGS. 7A-7Eillustrate portions of the capillary plate including valve orifice 91, alumen defined by the surface of channel 92, and outer surface of valveorifice 93. In some embodiments the valve orifice diameter (the innerdiameter of lumen defined by channel 92) is about 0.001-0.005 inches,for example, about 0.002 inches. In some embodiments the outer diameter93 is about 0.004-0.015 inches, for example, about 0.006 inches. Theother dimensions shown in FIG. 7A are also in inches. The lumen ofchannel 92 can be formed by, e.g., micro-drilling. The small innerdiameter of the valve orifice allows the orifice to act like a flowrestrictor. The channel 92 also has a very small diameter and thus alsoacts as a flow restrictor and can vary or tune the volume dispensed pera given period of time. FIG. 7E shows an end view of the orifice inwhich the darkened region in the middle is the lumen defined by channel92.

In some embodiments of assembling the solenoid shown in FIG. 6, an epoxyglue is injected into holes 92 in solenoid housing 82 to glue all of thesolenoid components together at the same time.

In a solenoid valve, a magnetic remanence can occur in the magneticmaterial after the magnetic field is removed. This can cause thesolenoid valve to stay open longer than desired. In the implantsdescribed herein, a valve which stays open longer than desired canresult in too much CO₂ being released into the internal chamber whichcan reduce the accuracy of the remote controller's tracking of theestimated fill volume, described below. In some embodiments the core isoffset (e.g., to the left in FIG. 6) by a certain amount, or a shim canbe disposed between core 84 and the spring assembly to reduce the amountof magnetic remanence. FIG. 8 shows the residual remanence force vs.core offset (in inches), showing that the further the core is offset,the less the remanence force.

The valve's performance can be tested by measuring the solenoid current(measured as voltage across a resistor) over time. The valve's open timecan be determined from this measurement to meet internal specifications.FIG. 9 shows an exemplary solenoid current measured over time, whichshows the “valve opening time.”

The volume of gas that is released by a canister each time the actuationbutton on the remote control is actuated can be determined duringtesting by weighing the canister after each time the button isdepressed. This volume determination is factored into the software asdescribed below.

FIGS. 10A-10C illustrate an exemplary embodiment of a magneticenhancement pad to prevent saturation of a central part of a spring. Aspiral spring is shown which can be used in the spring/seal assembly 86shown in FIG. 6. When current runs through solenoid coil 85, magneticflux is generated in the inner disc 102 and inner disk can becomemagnetically saturated. The spring as shown includes outer annularelement 100 and inner disc 102, which are connected by connectingportions 110 at hinge elements 104, 106 and 108. The spring alsoincludes a second disc 120 attached to disc 102 by, example, spotwelding. Second disc 120 helps to prevent the spring center frombecoming magnetically saturated and it responds better to the magneticfield (i.e., it has more magnetic permeability). This allows more forceto be applied to the central part of the spring to open the valve.

FIG. 11 illustrates a magnetic enhancement pad 132 that can be used asan alternative to disc 120 shown in FIGS. 10A and 10B. Pad 132 is formedwith a plurality of bores 134 therethrough generally around theperipheral portion of the pad. Creating the holes in the pad provides apad with less mass than disc 120, which does not have any holes. In use,once the magnetic field ceases, the spring assembly accelerates the pad132 (or disc 120) attached thereto toward the valve orifice, resultingin an impact (and therefore closing off the valve). A pad with lessmass, such as pad 132, applies less of an impact force on the valveorifice when the spring assembly moves towards the closed configuration.Less force applied by the pad translates into less wear on the valve,which adds reliability, safety, and increases the life of the valve.

In use, the implantable portion is adapted to be positioned within thepatient in a collapsed configuration in which the inner chamber is notin the expanded configuration. The collapsed configuration eases theinsertion of the implantable portion into the patient. The implant canbe positioned within the patient in any suitable location in whichtissue is to be expanded. In some methods of use, the implantableportion is positioned within a patient following a mastectomy. In suchembodiments the implant can be positioned in, for example, asub-muscular, partially submuscular, or subcutaneous position in theregion of the removed breast tissue.

After the implantable portion is positioned within the patient, theremote controller is actuated to release the fluid from the fluidreservoir, through the valve, and into the inner chamber. A “burp” isreferred to herein as the event in which fluid is released from thereservoir. The periodic or continuous release of the fluid into theexpandable inner chamber causes the inner chamber to expand over time,which causes the expansion of tissue proximate the implant. Once thetissue has been expanded to the desired degree of expansion, the implantcan be removed from the patient and a permanent implant can replace thetemporary implant.

The remote controller is adapted to control the amount of fluid that isreleased from the fluid reservoir over time. When the user actuates theactuator on the remote controller, the valve within the driver opens andreleases the fluid, such as CO₂, from the reservoir into the expandableinner chamber.

The tissue expansion system comprises various electronic components toperform the functions described herein. The electronic components can bedisposed in the remote controller, the implant, or some of theelectronics can be disposed in the controller while some are disposed inthe implant. In general, the tissue expansion system includes electroniccomponents that allow the remote controller to wirelessly communicatewith the implant and provide power thereto to control the release offluid from the fluid reservoir. In some embodiments, such as thosedescribed above, the implant includes an antenna adapted to communicatewith the driver. The antenna is adapted to be electromagneticallycoupled with an antenna in the remote controller upon actuation of theremote controller such that actuation of the remote controller inducescurrent to flow through the solenoid coil to open the valve, therebyreleasing the fluid from the reservoir. In this manner the remotecontroller is adapted to provide power to the implantable implant viainductive coupling. In order to facilitate the transmission of temporarypower to the driver, the antenna of the external device and theimplantable devices must be in within a certain range of each other.Transmission of power between the remote controller and the implant canalternatively be carried out through a radiofrequency link or othertypes of wireless links.

In some embodiments the remote controller includes a power source, suchas a rechargeable battery, to provide power to some or all of thesystem's electronic components. The implantable portion may alsocomprise a power source to provide power to electronic components withinthe implantable portion.

In some embodiments the electronic components may include one or morememory devices (e.g., RAM, Flash) to store information, such asinformation about the expansion of the expandable chamber.

The remote controller can also include one or more outputs for providinginformation to the patient as well as inputs for receiving instructionsfrom the patient. The outputs can include audio outputs, visual outputs,and tactile outputs such as vibrations. The inputs can be actuators suchas buttons, knobs, touch screens, microphones, etc.

The electronic components may optionally include circuitry and/or amicroprocessor adapted to execute software, such as, for example withoutlimitation, an algorithm that compares the total volume of gas that hasbeen released from a gas source into the expandable chamber with apreset maximum fill volume. The software can additionally be programmedwith limits on the dose amounts (including dose/burb, dose/time period)and the frequency with which doses may be administered. In someembodiments the processing component is disposed in the remotecontroller and includes any algorithms programmed with the limits on thedosages and with the limits on the frequency with which doses may beadministered. In some embodiments, when the remote controller isactuated, the processing component is adapted to compare the number oftimes fluid has been released from the fluid source within a givenperiod of time with a maximum number of times fluid is allowed to bereleased from the fluid source within the given period of time. If thenumber of times that fluid has been released within a given period oftime is greater than or equal to a maximum number of times fluid isallowed to be released from the fluid source within the given period oftime, the remote controller will not initiate the release of fluid fromthe fluid source (i.e., the valve will remain closed), and can befurther adapted to provide an output to the user, such as an audiblebeep or the illumination of lights to indicate that an error hasoccurred. In some embodiments the remote controller is adapted to turnoff. Exemplary limits that can be programmed into the processingcomponent include a maximum of 1 dose (which is made up of one or moreburps) about every hour to 1 dose about every 24 hours. In someembodiments the maximum dose is 1 dose about every hour, while in someembodiments the maximum dose is 1 dose about every three hours, but itcan also be, for example, two doses about every 5 hours. For example, ifthe limit is one dose every hour, and the user actuates the actuator twotimes within 1 hour, the remote controller will not release fluid fromthe fluid source upon the second actuation. These quantities are merelyexemplary and not intended to be limiting.

In some embodiments, when the remote controller is actuated, theprocessing component compares the volume of fluid that has been releasedfrom the fluid source within a given period of time with a maximumvolume of fluid that is allowed to be released from the fluid sourcewithin the given period of time. If the volume of fluid that has beenreleased within a given period of time is greater than or equal to amaximum volume of fluid that is allowed to be released from the fluidsource within the given period of time, the remote controller will notinitiate the release of fluid from the fluid source, and may provide anoutput to the user as set forth above. Exemplary limits that can beprogrammed into the processing component include a maximum volume limitfrom about 5 mL to about 100 mL every 24 hours. In some embodiments thedaily allowable volume is from about 10 mL to about 50 mL. For example,in some embodiments the daily volume limit is about 30 mL in about every24 hours. In use, a strict 24 hour limit can be burdensome on thepatient's daily routine, so a limit that is generally 24 hours (e.g.,20-22 hours) can be programmed into the system instead. These are allconsidered to be about 24 hours. In some embodiments the processingcomponent is programmed with a maximum 3 hour volume limit. For example,in some embodiments the system is programmed with a limit of about 10 mLfor about every 3 hours.

The processing component can also be programmed with limits on theamount of fluid that is released during a single dose, or during asingle burp. In some embodiments when the remote controller is actuated,a processing component is adapted to prevent more than a maximum volumeof fluid from being released from the fluid source. For example, in someembodiments the system can be programmed to release about 1 mL to about50 mL per dose, 1 mL to about 40 mL per dose, 1 mL to about 30 mL perdose, 1 mL to about 20 mL per dose. In some embodiments the system canbe programmed to release about 5 mL to about 15 mL per dose. In someembodiments the system is programmed to release no more than about 10 mLper dose. If the system detects that more than 10 mL has been releasedduring a single dose, the remote controller can be shut off, the valvecan be automatically closed, or other actions can be taken to preventadditional fluid from being released. In some embodiment the dose iscomprised of a plurality of burps. An integer number of burps can beused to approximate the desired dose, or a combination of full andpartial burps may be used to provide a more finely tuned dose amount.

The processing component can also be programmed to estimate the totalamount of fluid that has been released from the fluid source. Uponactuation of the remote controller, the processing component comparesthe total amount of fluid that has been released from the fluid sourceinto the inner chamber with a maximum fill volume for the implantablecomponent. This can prevent overexpansion of the implant beyond apre-established limit. If the processing component estimates that thattotal amount of volume released from the gas source is above a maximumfill volume, the remote controller will prevent the release of gas uponfurther actuation of the remote controller, unless, for example, aperiodic maintenance volume is required as described herein.

In some embodiments the implantable fluid is CO₂, and the CO₂ will leakout of the inner bag/outer shell assembly over time. While the inner bagcan be adapted to provide for a CO₂ barrier, some CO₂ will diffusethrough the layers of the inner bag over time. CO₂ can diffuse throughthe molecular structure of polymers, and is essentially impossible tocompletely contain within polymeric material. To determine the level ofCO₂ permeability through an inner compartment, a known amount of CO₂ isreleased into an inner compartment, and the inner compartment issubmersed in saline. CO₂ will diffuse through the inner compartment overtime and into the saline. Periodic measurements of the volume of theinner compartment are made over time, which provides for an estimate ofthe rate of CO₂ permeation. In some embodiments the inner compartment ispermeable between about 0 and 3 mL/day.

The processing component can be adapted to account for the permeationrate of the gas in some or all of its computations. For example, theprocessing component can factor the permeation rate into the totalamount of gas that has been released from the gas source toautomatically adjust the total of amount gas that is disposed within theimplant at any given time. The processing component can therefore allowfor a sufficient volume of gas, which is equal to that lost due topermeation, to be released into the expandable chamber to make-up forthe gas that permeated out of the implant. In use, after the fullexpansion of the implant has occurred, a patient may have to wait for aperiod of time (e.g., a month) before surgery can be performed toreplace the implant with a permanent implant. During this waiting periodsome CO₂ can diffuse from the implant. Under these circumstances it maybe necessary to perform periodic maintenance doses to release additionalCO₂ from the reservoir into the internal chamber to compensate for theCO₂ that has diffused through the inner bag. This can ensure the tissueexpansion remains at the level achieved after full expansion.

The system can include a re-programming key to allow a physician tomodify, or reprogram (permanently or temporarily) any of the programmedparameters using the re-programming key, a programming station, and/oran application on a separate electronic device, such as a computer orsmart phone. The limits can be overridden by a physician with the use ofthe physician master key (“PMK”), an example of which is shown in FIG.12. In FIG. 12, the remote control includes door 36, which can be openedto allow PMK 37 to be inserted to allow the physician to modify theexisting system parameters.

In some embodiments the remote control, or the implantable portion, orboth, include a memory component (either permanent of removable) whichcan store information relating to the use of the system, such as withoutlimitation, date/time, error conditions, bad cyclic redundancy check(“CRC”), doses delivered, battery voltage, status (on/off), number ofburps for a given dose, successful burps delivered, estimated volume oftotal gas in implant, estimate volume of gas remaining in the gassource, etc. The stored data can be extracted from the remote controllerby a variety of known means, such as by incorporating a USB port intothe remote controller, wirelessly downloading the information at aremote computer workstation, or transferring the information to aremovable storage device such as a flash drive.

The following steps are exemplary method steps that can be carried outin one or more methods of using any of the tissue expanders disclosedherein. Not all of the method steps necessarily need to be performedwhen using a tissue expander. The order of any of the steps can also bemodified in actual use.

Prior to initial use, the implant and the remote controller are bondedto one another, which prevents the remote controller from communicatingwith any other implant. The bonding step is typically performed bymedical personnel before the implant is implanted, but can occur afterthe implantation as well, and can also be performed by the patient. Insome embodiments the implant is one of four sizes and one of eightchannels, which results in 32 configurations. In some embodiments thebonding can be performed only after a bonding key is inserted into theremote controller. Once the bonding key is inserted and an implant isbonded to the remote control, the remote control is bonded to that modeland channel. The memory component, which can be disposed in the remotecontroller, reads and stores the following information from the bondingkey: implant model number, implant channel number, implant Volume Filllimit (cc), canister dose calibration including dispense rate (cc/burp),implant permeation rate (cc/day), and starting implant volume estimate(cc) (normally set to 0). The parameters stored in the remote controllerfrom the bonding step can be used in the limits calculations describedabove.

In an alternative embodiment, each implant includes a unique serialnumber chip. Before system use, a remote controller can be bonded onceto a unique implant using this unique serial number chip. Following thisbonding sequence, the remote controller will only recognize and dose anexpander with that unique serial number. Alternatively, all bonding datacould be stored in the implant and no key is used. The implant may haveinternal memory where it registers that it has been bonded to so that itwill not accept a bond to another controller.

After storing the implant data from the bonding key or other initialdata transfer, the total number of successful burps is set to zero, andthe running total of estimated gas released will be set to the startingimplant volume estimate. After storing the implant data, the remotecontroller erases this information from the bonding key to prevent itbeing downloaded by another remote control. A bonding key that has hadits implant data erased can, however, function as a master key in anydose remote control with which it is used. After storing the implantdata, the remote control enters into a detect mode.

Any of the following features can be programmed into one or moreelectronic components to occur during, e.g., the detect mode. Beforeentering detect mode, the remote controller updates the total implantvolume based on the permeation rate of the implant. Upon entering detectmode, the remote controller will compare the total implant volume withthe volume fill limit. If the total implant volume is equal to orgreater than the volume fill limit, the remote controller will providean output, such as an audio sound, or an illumination of the lightindicators, and the remote control will turn off. Other types of errorindication can be incorporated into the system. Upon entering detectmode, the remote control will compare the volume of gas released withinroughly the last 24 hours with the 24 hour limit. If the volume releasedis equal to or greater than the 24 hour limit, error alert(s) willoccur, and the remote control will turn off. Upon entering detect mode,the remote control compares the time since last successful dose to theminimum time between doses. If the time since the last dose is less thanthe minimum time between doses, an error alert will occur and/or theremote control will turn off. In detect mode if the remote control doesnot detect an implant, none of the indicator lights are illuminated. Indetect mode, if an implant is detected the remote control shall read itsmodel and channel number or serial number. In detect mode, if the remotecontrol detects an implant that matches its bonded model and channelnumber, with an unacceptable coupling level, it will emit a soundindicative of the distance from the acceptable coupling region, andlight a proportional number of the indicator LEDs of a given color. Indetect mode, if the remote control detects an implant that matches itsbonded model and channel number, with an acceptable coupling level, itwill play an acceptable coupling sound indicative of the distance fromthe maximum achievable coupling, and light four or five (proportionalwith the % of maximum possible coupling) indicator LED's of a certaincolor. If, while in detect mode, with the implant sufficiently chargedand the power coupling of a sufficient level to be able to complete thedose, the actuator in the remote controller is actuated to deliver adose. Sufficient charging and power coupling is indicated by the remotecontroller when 4 or 5 LED's of a given color are lit

The remote controller can be programmed to perform any of the followingfunctions while in dose mode. Upon entering dose mode the remotecontroller shall command the implant to release the desired dose whichis the lesser of the prescribed dose amount, the roughly 24-hour doselimit minus the dose given in the last 24 hours, the implant fill limitminus the total estimated gas released, and the prescribed dose amountminus the dose given in the last release (minimum time between doses). Aburp is generated by holding the implant valve open for about 0.250seconds+/−0.002 seconds, although this time is not intended to belimiting. The dose shall be applied by commanding an integer number ofburps. The remote controller shall wait a minimum of 0.250 secondsbetween burps. The number of burps applied in a given dose shall becalculated such that neither the roughly 24 hour dose limit nor theimplant fill limit will be exceeded; the prescribed dose should not beexceeded by more than about 25%. The memory component can store ahistory of the time and estimated successful total volume deliveredafter each dose. The memory component maintains a running total of theestimated total implant volume. The memory component maintains a runningtotal of the number of successful burps administered. The processingcomponent can calculate the amount of gas released per burp based on therunning total of the number of successful burps administered and thecanister dose calibration provided at the time of bonding. Betweenburps, if the remote controller detects that the implant is not makingadequate progress charging the implant, it shall indicate a failed doseand return to detect mode. Between burps, if charging takes more than aspecified amount of time (e.g., 3 seconds), the remote controllerindicates a failed dose by providing an appropriate output to thepatient (e.g., a visual or audio output), and then returns to detectmode. Before each burp the remote controller shall verify that theimplant model and channel number match the remote controller's bondedimplant and model number. If they do not match the remote controllerwill provide an error output and turn off.

As discussed above, a master key can be used to override the programmedlimits of the system to allow a physician to control the release offluid outside of the set limits. When a master key is positioned in theremote controller or is in communication with the remote controller, the24 hour maximum limit can be over ridden. When a master key is in theremote control, the minimum time between doses shall be set to 0. When amaster key is in the remote control, all doses shall be the prescribeddose. When the prescribed dose is not made up of an integer number ofburps, a remote controller with a master key can round up the appliedburps per dose. After the master key is removed from the remotecontroller, the previously programmed limits shall again be enforced.

The system optionally includes a limit key, which is a key that can beinserted into the remote controller and used to replace the originallimits with those stored on the limit key. When a limit key is detected,the remote controller shall replace its stored limits with those fromthe limit key. After the new limits have been stored, the controllershall re-read the limits from the key and compare them to the storedlimits. After successfully programming the limits, if the key is removedthe device enters detect mode.

The system can optionally include an override key which is adapted to beinserted into the remote controller. When an override key is in theremote controller, the 24 hour maximum limit shall be overridden; theminimum time between doses shall be set to 0; the maximum fill limitshall be overridden; and all doses shall be the prescribed dose. Whenthe prescribed dose is not made up of an integer number of burps, aremote controller with an override key can round up the applied burpsper dose. When an override key is inserted, the remote controller shallwrite the contents of its log file to the override key. When writing thelog file to an override key, the remote controller may overwriteprevious log files. Log files on the override key shall contain a headerincluding the date and time file was written, and model and channelnumber of the implant the controller is bonded to. After the overridekey is removed from the remote controller, previously programmed limitsshall be enforced.

In some embodiments the memory component maintains a log file ofspecified system interactions. For each requested dose an entry is madein the log file comprising: date and time, number of burps calculatedfor that dose, number of successful burps in that dose, and implantvolume estimate at the end of the dose. Each time the remote controlleris turned on a log entry can be made comprising: date and time, implantvolume, and battery voltage. Before the remote controller turns off theremote controller can make an entry in the log file including: date andtime, number of bad CRC messages since power on, and the last errorcode. In the event of log file memory limitations, the newest recordsshall be retained and oldest records erased (first-in-first-out).

In some embodiments the memory component stores treatment and devicefunctionality information. In some embodiments the information is storedin the implant and the remote control can therefore be universal—theremote control is not bonded to a specific implant and nopatient-specific data is stored on the remote control.

The disclosure above describes some exemplary methods of use in thecontext of the remote control functionality (e.g., bondingfunctionality, master key overriding, etc.). An exemplary quickreference guide for a physician is shown in FIG. 13. FIG. 14 illustratesan exemplary quick reference guide for a patient which provides dosinginstructions. In addition to the patient dosing instructions, oneexample of the implantable device suggests that the patient should beadvised not to travel by air during expansion, not to travel by groundtransportation involving an ascent greater than about 1000 meters, andthat if pain is increasing in severity over several hours, not to addmore volume and to call the physician.

In some embodiments the physician will choose an implant from a kit ofimplants, or from a number of implant sizes which are available. Thesize of the implant can be based partially on patient parameters, suchas the chest wall dimensions of the patient. In some embodiments theimplants are 20% larger in volume than the corresponding permanentimplant. Table 1 provides an exemplary list of 4 differently-sizedimplants and their respective properties, from which the physician canselect one for implantation.

TABLE 1 Implants Pro- Shape/ Width Height jection Volume Surface ProfileSize (cm) (cm) (cm) (cc) Textured Anatomical Small 10.5 10.0 9.0 400Textured Anatomical Medium 12.0 11.0 10.0 650 Textured Anatomical Large13.0 12.0 11.0 850 Textured Anatomical Full 14.5 13.5 12.0 1100

The guiding aspect of dosing is dependent on patient comfort. If thepatient is experiencing only minimal discomfort, the release of gas cangenerally be continued, according to the limits on the parametersprogrammed into the system. Allowing the patient to control the amountof tissue expansion based on the level of discomfort provides anexemplary advantage over other tissue expansion techniques because theexpansion can occur more continuously than previous treatments, whichmay allow for lower pressures and less total expansion time.

Once the labeled volume of the implant has been achieved, the ability toadd additional volume is significantly decreased to avoidover-pressurization of the implant. At this point, the processingcomponent will generally only allow for a volume release equal to theslow permeation of gas from the gas reservoir.

In some embodiments the implantable portion includes one or morepressure relief valves that are configured to relieve a specific amountof gas from the expandable inner chamber to relieve pressure within theinner chamber. A potential use for the pressure relief valve is inaltitude management. As the altitude of the patient in which the implantis implanted increases, the external pressure decreases and the gasinside the implant expands. In some embodiments the system includes apressure sensor, which can be in the implantable portion or the remotecontroller (which should be maintained at the same altitude as thepatient during travel). The pressure sensor monitors thepressure/altitude, and the memory component can log readings. If thepressure sensor is disposed within the remote controller, the remotecontroller can be adapted to monitor the pressure each time it is turnedon, or to make periodic pressure readings while it is turned on. Theremote controller can be adapted to control opening of the pressurerelief valve in the implantable portion, either automatically or afterprompting a user to actuate the remote controller. In some embodimentsthe pressure sensor is disposed within the implant, and if the implanthas a power source it can automatically open the pressure relief valve,or the sensor could send a communication signal to the remote controllerto alert the patient to actuate the remote controller, which would openthe relief valve. The remote controller can be adapted to have a firstactuator to release gas from the reservoir and a second actuator (suchas a button) to control the opening of the relief valve.

The memory component in the system can also record the volume of gasthat has been vented from the implant. The volume record would be usedto calculate how much gas should be released from the canister tocompensate for the vented gas after the patient has returned to a loweraltitude. The remote control can also be adapted to provide an output towarn the patient if the venting is too frequent so that sufficient gasdoes not remain within the gas reservoir to compensate for the ventedvolume.

FIGS. 15A-H illustrate exemplary relief valve concepts that can beincorporated into any of the tissue expander systems disclosed herein.In some embodiments, the pressure is released from the inner chamber andthe relief valve does not reseal. In others, the relief valve has thecapability of resealing.

FIG. 15A illustrates a portion of an implant in which at least a portionof the barrier layer 150 of the inner bag is bonded to an inverted dome152. When the pressure “P” inside the inner bag increases, it can causedome 150 to invert, or pop out, causing the piercing element 154 topierce a portion of barrier file 150, releasing gas out of the innerchamber. Piercing component 154 can be bonded to another part of theinner bag, or even to the outer shell.

FIG. 15B illustrates a portion of an implant in which a first portion156 of the barrier film and a second portion 157 of the barrier film arebonded together at location 158, such as by heat staking. As thepressure “P” inside the inner chamber increase, it causes the heatstaked film to separate, releasing gas out of the inner chamber.

FIG. 15C illustrates a portion of an implant in which a piercing element159 is formed or secured to a heat staked area. When the pressure “P”inside the inner bag increases enough, the piercing element will piercethrough the inner bag and release gas from the inner chamber.

FIG. 15D illustrates a portion of an implant in which film 162 issecured to barrier layer 164. Lever arm 166 includes a magneticmaterial, as does magnetic ring 168. As the pressure “P” inside theinner chamber increase, film 162 bows as indicated, moving lever arm 166away from magnetic ring 168. This allows gas to escape in the directionof arrow G shown.

FIG. 15E illustrates a portion of an implant in which lever arm 170rotates about point 178 as it is pushed by film disc 172, when the filmdisc is under pressure. After arm 170 rotates to a certain degree, thearm's piercing element 174 snaps into a second region of the film disc.This releases gas from the inner chamber.

FIG. 15F illustrates a portion of an implant in which foil (or othersuitable material) dome 180 is adapted to invert upon an increase inpressure “P.” When it inverts, the regions 182 where the stress inconcentrated will tear, allowing gas to escape from the inner chamber.

FIG. 15G illustrates a portion of an implant in which magnetic materials190 and 188 bias the film inward. As the pressure “P” inside increases,film 186 bows outward as shown, wherein the plurality of piercingelements 192 pierce the film 186, allowing gas to escape.

FIG. 15H illustrates a portion of an implant in which film 194 ismaintained between layers 198 of a rupture disc. The rupture discincludes a failure initiating indent 196, which is adapted to tear film194 as pressure “P” increases and pushes film 194 into indent 196.

In some embodiments a valve includes a magnetic material and the valveis opened when a second magnetic material is moved in close proximity tothe first magnetic material. This vents the gas and deflates the tissueexpander prior to, for example, radiation therapy. The valve can bere-sealable. When the magnet is removed, the valve closes and the innerbag can be re-filled with additional gas from the reservoir in thedriver. This approach can also be used to vent gas if the patient has totravel to altitude and is experiencing pain or discomfort from theexpansion of the gas within her implant. Alternatively, the inner bagcan be filled with a liquid such as saline using any of the methodsdescribed below. In some embodiments the relieve valve is electronicallyactivated an actuator housed in the remote controller.

FIGS. 16 and 17 illustrate an exemplary embodiment of a pressure reliefvalve with a resealing capability that can be incorporated into any ofthe tissue expanders disclosed herein. As shown in FIG. 16 the pressurerelief valve includes flow control tube 270 fixed and sealed to an outervalve housing 267 using adhesive. Inner valve housing 265 is threadedinto outer valve housing 267 and retains spring/seal assembly 264 andshims 266 that determine the desired amount of valve opening. Valve seat271 on the end of flow tube 270 is smoothed to insure a leak-free sealwith the elastomer portion of spring/seal assembly 264 when the valve isclosed. Valve magnet 263 is mounted and fixed to spring/seal assembly264 using adhesive. The valve housings are retained within retentionring 261 that provides the ability to heat seal 262 the valve to innerbag 260. Retention nut 269 compresses seal washer 268 and the portion ofretention ring 261 between outer valve housing 267 and seal washer 268,thus, providing a seal between the valve housing and the retention ring.

As shown in FIG. 17, the valve is opened by bringing control magnet 275into close proximity to valve magnet 263. This causes the valve magnetthat is attached to the spring/seal assembly to move in the direction ofthe arrow. The movement of the spring/seal assembly opens the valve,allowing gas to flow out of the inner chamber through the lumen of flowcontrol tube 270 and past valve seat 271 as indicated by the arrows.

Some embodiments of the tissue expander are adapted to have fluidremoved after the fluid has been released from the reservoir into theinner chamber inside the patient. An example of this is the use of thepressure release valves described above to release gas from the innerchamber when the pressure becomes too great. There are additionalpotential situations in which it is desirable to release, or remove,fluid from the implant. For example, some current radiation therapyprotocols for women who have undergone a mastectomy involve deflatingthe tissue expander after it has been expanded within the patient,therapeutically radiating the tissue, and then re-expanding the deviceagain after completion of radiation therapy.

Some of the embodiments that provide for the release of gas from theimplant provide for one or more of the following features: 1) deflatinga gas-filled expander by venting the gas, in some embodiments inside andin others outside of the body; 2) re-inflating the expander with a fluidsuch as saline or gas. Any suitable components of any of the embodimentsdescribed below may be incorporated into a tissue expansion system toprovide a pressure relief valve.

If re-inflating the expander with saline, the outer shell (which can becomprised of silicone material) is adapted to retain saline liketraditional saline expanders. In some embodiments described above,however, the outer shell is perforated to allow air between the innerbag and the outer shell to escape for ease of insertion into the patientduring implantation. In embodiments with a sealed outer shell to retainthe saline, there would therefore be a requirement for an alternatemethod of venting air from between the inner bag and the outer shellduring implantation.

These embodiments provide the physician the option of implanting adevice that could be deflated and subsequently re-inflated. It also mayprovide the physician the option of forfeiting such a capability byremoving the components which provide this functionality from theprimary expander, such as in cases where the likelihood ofpost-operative deflation/re-inflation is very low (prophylacticmastectomy, small tumors far from the chest wall, etc.). Thus, a portionof the device could be removed if desired.

FIGS. 18A-C show a portion of an exemplary implant that includes dockingport 224 formed integrally with outer shell 223. One-way remote valve222 is secured to outer shell 223. Docking port 224 and valve 222 areadapted to receive device 225 that is adapted to release fluid from orfill fluid into the implant. Device 225 has fill/drain tubing 226 andneedle injector tubing 227 each terminating with a Luer fitting 229 and228, respectively. Device 225 also includes fenestrating cannula 230,compression spring 231, piston 232, and seal 233.

In FIG. 18A, one-way valve 222 is in a closed configuration, and cannulaor needle 230 is retracted inside device 225. Until central cannula 237is docked with port 224, the one-way valve remains closed and air istrapped between the inner bag and the outer shell. The inner bag isintact and provides the gas barrier within the tissue expander.

Prior to implantation of the implantable portion into the patient, anyair that has diffused through the outer shell (shown in FIGS. 18A and18B as made out of a silicone material) into the space between the innerbag and the outer shell may be removed. If it is not removed, theimplant will feel partially inflated and will make insertion to thetarget region more difficult. FIG. 18B shows device 225 docked with port224, and cannula 237 has forced valve 222 into an open configuration,creating a passage for air to flow from the space between the inner bagand the outer shell. Air 234 trapped between inner bag 220 and outershell 223 can be vented from the space between inner bag 220 and outershell 223 using a syringe attached to fill/drain tube 226, as indicatedby the directions of the arrows shown. In FIG. 18B, inner bag 220remains intact and continues to provide the gas barrier within theimplant. Fenestrating cannula or needle 230 remains withdrawn insidecentral cannula 237.

FIG. 18C illustrates a use of device 225 and valve 222 to remove gasfrom the inner chamber of the implant. As mentioned above, some patientsrequire radiation therapy after a tissue expander has been expanded. Ifthe patient requires radiation therapy and the protocol recommendsdeflation of the implant prior to radiation therapy, gas in the implantmay need to be removed. Needle injector tube 227 is filled withpressurized liquid (either through a fitting exposed through the skin orvia a remote fill valve punctured with a transcutaneous needle). Thepressure from this injected fluid displaces piston 232 upward,compresses spring 231, and deploys fenestrating cannula 230 from centralcannula 237, causing cannula 230 to puncture inner bag 220 at location235. Gas “G” is then vented through cannula 230 and out of tubing 226,as illustrated by the direction of arrows. In some embodiments the gasis vented outside the body. The action shown in FIG. 18C irreversiblypunctures inner bag 220, converting it to a fluid controlled expandersimilar to saline expanders currently on the market. After the radiationtherapy or other therapy is complete, port 242 can be located, puncturedwith a needle and the inner chamber can be filled to the desired volumewith a fluid such as saline.

FIG. 19 illustrates a portion of an alternative embodiment of an implantwith a dedicated docking port 242 at a separate location on outer shell241. This design separates the feature for venting air from the spacebetween the inner bag and outer shell from the implantdeflation/inflation feature. Tubing 246 is coupled to central dockingcannula 248 (similar to the central cannula in FIGS. 18A-C) and luerfitting 247. This device does not have a fenestrating, spring-loadedcannula with the second piece of tubing as shown in the variation inFIGS. 18A-C. The device in FIG. 19 can be used to aspirate air frombetween inner bag 240 and outer shell 241 prior to implantation. Priorto implantation, cannula 248 and tubing 246 are removed from dockingport 242.

One advantage of the approach in the embodiment in FIG. 19 is that iteliminates the implantation of the remote fill port. A temporary tubingis used to remove the air from the space between the inner bag and theouter shell (as shown in FIG. 19) and then is detached from the implantprior to implanting the implant within the patient. The outer shell isdesigned to hold saline at pressures encountered during tissueexpansion.

The implant shown in FIG. 19 can additionally include an intrinsicinjection port such as the injection port shown in FIG. 20 to removefluid such as gas from the inner chamber. Deflation of the implant priorto radiation therapy is accomplished by targeting and inserting a needle256 (e.g., 25 G) into intrinsic port 251 which can be disposed in theanterior, superior portion of outer shell 250 for ease of locating.Needle 256 passes through 251 intrinsic port and penetrates inner bag252. Once the inner bag is breached by the needle, gas in the innerchamber can be vented from the implant into the ambient atmosphere.

Antenna 253 can be constructed of a tough material such as a polyimidematerial that resists needle penetration. In some embodiments, theantenna is heat staked continuously with a gas impermeable membrane 254to the inside of inner bag 252. As shown in FIG. 20, this type ofassembly can be modified to allow gas “G” to escape. In particular, ventholes 255 can be formed around the antenna which allows gas from withinthe implant to pass therethrough and out through needle 236.

Once radiation therapy is complete, needle 256 can again be insertedinto intrinsic port 251 and saline can be injected into the innerchamber to achieve the desired volume. During re-inflation, the needleneed not penetrate the inner bag. Saline only needs to fill the outershell to the desired volume.

In embodiments that include an intrinsic port, the intrinsic port caninclude any or all of the following features: the needle port is in thesuperior anterior portion of the implant and reseals after repeatedinsertions of a needle; it is robustly attached to the elastic materialof the inner bag so that pressurized saline will not leak out of theinner bag; and a needle stop to prevent the needle from fenestrating theposterior panel of the implant and causing a leak. It is noted that theintrinsic port concepts shown can be implemented with or without anintegral needle stop. Additionally, if the intrinsic port does notinclude an integral needle stop, alternate methods of protecting theposterior panel of the inner bag can be employed (not shown in thefigures, but it can be accomplished, for example, by reinforcing theposterior panel with impenetrable component-like polyimide film).

In tissue expander implants that include antennas, the injection pointcan be located in the middle of the antenna and its location can beestablished using the antenna-locating ability that exists in the remotecontroller. Alternatively, a separate external device specificallytasked to locate the antenna and port can be developed with an integralneedle guide. This locating needle guide can use the electromagneticcoupling with the antenna to guide the needle into the desired zone forneedle puncture.

The exemplary embodiments described in FIGS. 21-24 illustratealternative intrinsic needle ports, and illustrate how an intrinsicneedle port can be attached to an anatomically-shaped inner bag of atissue expander to maintain a leak-proof, saline-filled bladder and topreserve the low permeation performance of the inner bag. Configurationsare shown both with and without a component acting as a needle stop.

FIGS. 21A and 21B illustrate an exemplary embodiment of an implant withan intrinsic needle port. The intrinsic port as shown includes asilicone re-sealable injection port 264 molded around port flange 265(see FIG. 21A). Since port flange 265 is insert molded within thesilicone port 264, a leak-proof connection between the two componentsretains saline within the implant. Port flange 265 is shaped like awasher with a raised rib to improve the durability of the connectionbetween it and injection port 264. Port flange 265 can be made from athermoplastic material such as polyethylene to facilitate attachment toinner bag 261 with either a heat staking or ultrasonic welding, forexample. Heat staking provides a leak-proof attachment. Antenna 263 isshown outboard of injection port 264 and is made from flexible circuitmaterial such as polyimide encapsulated copper traces. It is positionedand fixed coaxially with injection port 264 using a thin film ofthermoplastic, such as polyethylene, using heat staking or ultrasonicwelding methods. Antenna 263 and injection port 264 are retained byantenna patch 262, which is also heat staked to inner bag 261.

Prior to the use of the needle and in embodiments in which gas is usedas the initial filling medium, injection port 264 is mounted so thatinner bag 261 remains completely intact until needle puncture. Thisensures that inner bag 261 does not excessively lose gas due topermeation through injection port 264 or its attachment point.

When injection or aspiration is required, needle 267 is inserted throughouter shell 260, through inner bag 261, and into port 264, and throughantenna patch 262 and into the inner compartment. When the needle isremoved, the liquid contents of the implant can pass through antennapatch 262 through the hole created by needle 267 and pool belowinjection port 264. However, liquid cannot pass through siliconere-sealable injection port 264 or around injection port 264 to escapethrough the needle hole in inner bag 261 located above injection port264. Inner bag 261 therefore remains inflated with saline with no leaks.

FIG. 21B shows the embodiment from FIG. 21A but includes needle stop268. The needle stop is incorporated in this assembly by placing acomponent below injection port 264. The needle stop can be a plastic ormetal disk such as polyimide. In the embodiment shown, the needle stopis combined with the antenna (combined as 268) to make the overall portmore compact. To position and fix needle stop 268 below the port, a thinfilm 262 of thermoplastic material such as polyethylene can be heatstaked to the inner bag.

The embodiments in FIGS. 22-24 have similar architectures to theembodiment shown in FIGS. 21A and 21B. An exemplary difference is thespecific method of attaching the silicone injection port to the innerbag film in a robust, leak-proof manner.

FIGS. 22A and 22B illustrates a method of attaching silicone injectionport 274 to inner bag film 271 in a robust, leak-proof manner. Plasticring 275 with a threaded portion and a thru hole is heat staked to theinside of inner bag 271 at region 278. Injection port 274 is mountedwithin ring 275 and is retained by plastic nut 276. Flange portion 281of injection port 274 is crushed as plastic nut 276 is tightened, thuscreating the seal. Antenna 272 is retained in place by patch antenna273. A needle can be used in the same way as illustrated in FIG. 21A,passing through opening 277 in nut 276.

FIG. 22B shows the addition of needle stop 280 retained in position byneedle stop patch 281 in a similar manner to the embodiment in FIGS. 20Aand 20B. Alternatively (not shown), plastic nut 276 can be constructedwithout a through hole through the middle of the nut providing athickness of material to stop the needle. Additional vent holes can beadded to the plastic nut in a region away from where the needle mightcontact such as through holes that exit radially from the nut. Ventholes 279 are formed in patch 281 to allow gas to pass in and out of thepatch 281 into the port area. A needle can be used in the same way asillustrated above.

FIGS. 23A and 23B illustrate a method of attaching silicone injectionport 287 to inner bag film 286 in a robust, leak-proof manner. Crimpingcomponent 288 is shaped like a grommet and can be fabricated from metal.When deformed with the proper tool, the crimp can pinch and capture botha flange on injection port 287 and the inside region of washer 291 madeof thin plastic film. Crimp 288 forms a waterproof seal between thesecomponents. Subsequently during assembly, plastic washer 291 can be heatstaked to the inside of inner bag 286 at location 292. Antenna 289 ispositioned outboard of crimp 288 and retained by antenna patch 290,which is heat staked to the inside of inner bag 286. A needle can beused to penetrate into the implant though shell 285 as set forth above.

FIG. 23B shows the addition of needle stop 294 retained in position byneedle stop patch 295 in a similar manner to the embodiments in FIGS. 21and 22. Similar components to those in FIG. 23A have the same referencenumber.

FIGS. 24A and 24B illustrates a method of attaching silicone injectionport 404 to inner bag film 402 in a robust, leak-proof manner. Insertring 406 and nut 408 are used to clamp three thin members together: theflange from injection port 404, thin film 414 shaped like a washer, andsilicone washer 410. As shown in FIG. 24A, this clamping action forms awaterproof seal between these components. Subsequently during assembly,plastic washer 414 can be heat staked to the inside of inner bag 402 atregion 418. Antenna 412 is positioned outboard of injection port 404 andretained by antenna patch 416, which is heat staked to the inside ofinner bag 402. Vent holes 418 are formed in patch 416 to allow fluid topass therethrough. A needle can be advanced through the port asdescribed herein.

FIG. 24B shows the addition of needle stop 420 retained in position byneedle stop patch in a similar manner to the embodiments shown in FIGS.21-23. Other components are listed with the same reference number as inFIG. 24A.

While some of the embodiments described above are initially expandedwith a gas, it may be recommended that some patients not be implantedwith a device that is expanded with gas. For example, some patients maylive in mountainous regions or may be required to travel by air or athigher elevations for their work—both activities could cause discomfortor pain if using a gas medium that will expand in the decreasingatmospheric pressure encountered at higher elevations. A physician mayelect to use conventional saline-filled technology for a patient withthese travel needs. In some embodiments described herein the tissueexpanders include an anatomically-shaped inner bag. In-vivo, thisanatomical shape provides subcutaneous volume in the desired location(e.g., the lower pole for breast implantation) where additional skin isneeded. Saline-filled elastomeric tissue expanders generally do notaccomplish this. For breast reconstruction, the elastomeric (silicone)tissue expander often takes the shape of a round balloon expandingtissue undesirably in the upper pole. Occasionally, the liquid-filledelastomeric balloon will expand laterally (under an arm) or superiorly(toward the clavicle). Traditional saline-filled tissue expanders canthus be improved by incorporating an anatomically-shaped component, suchas the anatomically-shaped inner bags described herein.

Additionally, as described above, patients may also be identified earlyin their clinical treatment for breast cancer as needing radiationtherapy. If several deflation and re-inflation cycles are indicated, aphysician may elect for a more conventional saline-based expansiontechnology. Additionally, gas-inflating tissue expanders described aboveinclude a driver within the implant. The driver amounts to a mass ofmetal. Although saline expanders also contain metal, radiationoncologists may prefer not to plan their radiation dosing scheme withthe new metallic components of the systems described herein until theyare more familiar with it. Thus, anatomically-shaped, saline-filledtissue expanders could be an alternate solution for patients undergoingplanned radiation therapy. In some embodiments a traditionalsaline-filled breast implant is enhanced with a component with ananatomical shape to ensure that additional skin is created where it isneeded.

Additionally, some breast reconstruction patients do not have sufficientskin in the post-mastectomy region to cover a gas expanded tissueexpander. The driver of the gas expander may add more bulk andprojection to the tissue expander compared to a conventionalsaline-based tissue expander. A small percentage of breastreconstruction patients, whether undergoing immediate or delayedreconstruction, may benefit from a very low profile tissue expander.Anatomically-shaped, saline-filled tissue expanders with an intrinsicport could be very low profile solution for these patients. Theintrinsic ports described herein can therefore be incorporated intotraditional saline-filled expanders to provide for an expander with adesired anatomic shape, one that is comprised of relatively little metalto avoid radiation scattering during radiation therapy, and/or can beimplanted with a very low profile.

Generally, the inner chamber of the implant should be sterilized in theevent that a procedure must be performed on the patient that involvespuncturing the inner chamber while it is inside the patient. Sterilizingplastics, which are included in the implants disclosed herein, withelectron beam sterilization (“E-beam”) or gamma sterilization can,however, cause the materials to become brittle and/or lose some of theirproperties. The electronic components of the implant can similarly bedamaged from E-beam and gamma sterilization.

In some embodiments the inner chamber of the implant is sterilized witha gas such as ethylene oxide (“EtO”). The inner chamber, however, cannotsimply be exposed to EtO because the gas cannot pass from outside theinner bag to the inside of the inner bag. During the manufacture of theimplant, an inlet channel is provided from the inside of the inner bagto the outside of the inner bag, with a filter disposed over the outletof the channel. The inner bag with the filter and channel assembly isthen placed in the EtO chamber. The EtO passes through the filter, intothe channel, and into the inner bag of the implant, sterilizing theinner bag. The filter is designed to keep any bacteria from entering thechannel, but allows the gas to pass through it. A vacuum is then appliedto the inner bag, removing the air from the inner bag, and the channelis heat-sealed shut, leaving the inner bag sterilized. The inner bag isthen secured to the inside of the outer silicone shell. Next, the outershell with the sterilized inner bag therein is placed in the EtOchamber, which sterilizes the outside of the inner bag and the siliconeouter shell, as well as the rest of the packaging. The implant cantherefore undergo a two-stage gas sterilization process without riskingdamage to the materials or the electronics.

If the implant includes a pressure relief valve with the capability toreseal, the pressure relief valve could be shipped in an open positionto the sterilization facility. The inner bag could be held open for gassterilization on the inside of the inner bag. There could also be avalve designed specifically for sterilization incorporated into theinner bag (either mechanical grenade pin or electrically activated byfixture or the remote control). In some embodiments the implant can bepackaged with the valve open, followed by EtO sterilization. A vacuum isthen applied to the inner bag, followed by closing the bag valve forfinal shipment. In some embodiments, the internal portion of the driveris sterilized separately from the rest of the inner bag using Tyvek™ tocover the vent holes in the solenoid to maintain the sterility of theinner volume and driver parts.

FIGS. 25A-D illustrate an exemplary method of creating a filter andtunnel system to sterilize the inside of inner bag 200 with EtO. FIG.25A shows filter 208 in communication with inlet tunnel 206, in whichpin 202 is disposed to keep the tunnel from collapsing during the vacuumstages of the EtO sterilization. FIGS. 25C and 25D illustrate the stepsof positioning port clamp 201 and hand tightening thumb nuts 203,respectively, which provide access to draw vacuum on the inner chamber.

In some embodiments there is a final inspection of the packaged,sterilized product. The final inspection allows confirmation of bothvalve function and a leak check of the implant inner bag. The valvefunction can be verified by recording and analysis of the sound producedduring solenoid valve opening when the valve is actuated by the remotecontrol, i.e., “burped.” In some embodiments, the sound can be detectedand recorded using a contact microphone and then be subsequentlyanalyzed using computer software to confirm that the valve opened andalso determine the amount of time that the valve opened. The leak checkof the final sterilized product is accomplished by using the remotecontrol to actuate the valve and release a small amount of gas, i.e.,burp the implant, while the implant remains in its package. The implantis then pressurized to squeeze gas out of any potential leak path andmonitored with a sniffer specific to the gas used. The presence ofexcess gas indicates a leak.

In addition to any of the benefits described above, any of the tissueexpansion systems described herein can provide one or more of thefollowing advantages to the patient over previous tissue expansionsystems (some of which may be described above): less discomfort; noneedles are required; faster—complete reconstruction sooner; more rapidreturn to normal activity; fewer office visits; and ease of use.Advantages for the physician include no needles or office preparationtime; reduced expansion time; earlier completion of reconstruction; easeof use; greater patient satisfaction; and less chance of complicationsthan with injection-filling.

While preferred embodiments of the present disclosure have been shownand described herein, it will be obvious to those skilled in the artthat such embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the disclosure. It should beunderstood that various alternatives to the embodiments of thedisclosure described herein may be employed in practicing the invention.

1. A tissue expansion system, comprising: an implantable tissue expandercomprising an expandable chamber completely surrounding a compressed gasreservoir, wherein the expandable chamber is adapted to be a non-elasticchamber with a pre-formed breast shape when the expandable chamber isinflated with a gas from the compressed gas reservoir, wherein thepre-formed breast shape has a lower pole extension; and an externalcontroller adapted to wirelessly communicate with the implantable tissueexpander to control the release of gas from the compressed gas reservoirinto the expandable chamber to expand the expandable chamber.
 2. Thetissue expansion system of claim 1 wherein the expandable chambercomprises a generally flat posterior backing, and wherein the compressedgas reservoir is secured to the generally flat posterior backing.
 3. Thesystem of claim 1 wherein the expandable chamber comprises an anteriorportion having the pre-formed breast shape with the lower poleextension.
 4. The system of claim 3 further comprising a communicationcomponent secured to the anterior portion, the communication componentadapted to communicate with the external controller.
 5. The system ofclaim 4 wherein the expandable chamber comprises a generally flatposterior backing.
 6. The system of claim 5 wherein the compressed gasreservoir is secured to the generally flat posterior backing.
 7. Thesystem of claim 5 wherein the generally flat posterior backing issecured to the anterior portion.
 8. The system of claim 1 wherein theexpandable chamber comprises a posterior backing, and wherein thecompressed gas reservoir is secured to the posterior backing.
 9. Thesystem of claim 8 wherein the posterior backing is secured to ananterior portion having the pre-formed breast shape with the lower poleextension.
 10. The system of claim 9 further comprising a communicationcomponent secured to the anterior portion, the communication componentadapted to communicate with the external controller.
 11. The system ofclaim 1 wherein the expandable chamber comprises a pressure relief valveadapted to release gas from the expandable chamber.